Electric switch



July 28, 1941?.l L M PERSONSv v 2,29L502 ELECTRIC SWITCH Filed April 20, 1938 -2 Sheets-Sheet l ,qrroeA/EK AWM-WCE f4? PERS OMS,

July l28, 1942. l.. M. PERSONS ZZQLSOZ ELECTRIC SWITCH the device with the snob Patented July 28, 1942- ELECTRC SWETCH Lawrence M.. Persons, St. Louis,

Automatic Control Corporation,

Mo., assigner to St. Louis, Mo.,

a corporation of Delaware Application April zo, "ross, sei-iai No'. scacco (Cl. 20G-8?.)

9 Claims.

The present invention relates to a mechanism including a power transmission means for transmitting and multiplying the movement from a power source to a switch or the like.

In particular, the mechanism includes a dia phragm type expanding power means acting on a compound lever system with adjustments oi the connection between the lever system and the power means so as to vary the range of the mechanism, and also an adjustment of the i'ula crum of atleast one of the levers to eect a divided iulcrum, whereby the switch operates with a dierential.

An object of the invention is to provide a simple and convenient structural arrangement whereby the diaphragm mechanism may he tached; and a simple arrangement for the power take ofi stud. Y

.a further object oi the invention is to aren vide in a switch of this hind, a particularly et cient type oi pivot for the levers.

il `further object oi the invention is to idroN vide a particularly simple and convenient difg1 ierential mechanism.

in the drawings:

Fig. i is a iront elevation oi the device;

Fig. 2 is a side elevation looking from the leit or Fig. l with. the cover in section and the irame partly hrolten away;

Fig. 3 is a rear elevation with the cover in section;

Fig. i is a iront elevation of the upper haii oi and dial removed;

Fig. 5 is a horizontal section at the top oi the device, on the line --i of Fig.. 2;

Fig. 6 is a vertical midsection on the line of Fig. i;

Fig. Z is a horizontal section through the axis of the diaphragm on the line ll-l or' Figs. 2 and 6;

Fig. 8 is a horizontal section at the `loottoiu oi the device on the line 3 3 of Fig. 2;

Fig. 9 is a vertical section at the lower middle of the device on the line 9-9 of Fig. d, showing the outerw` end of the switch blade or secondary lever;

Fig. l0 is a section on the line lillll oi t;

Fig. l1 is a View of the differential adjusting lever; and,

Fig. l2 is a view of the primary lever.

A front #plate 2B has attached thereto a .main frame 2i, U-shaped in cross section, as appears in Figs. 5, 7 and 8, and with which the iront plate .forms an open ended housing. Projections 22 at suitable points on the frame 2l pass i Si is provided between the flange 3l on through the iront plate 2t and are peened over to secure the frame and plate together.

A cover 23, likewise of U-shape cross section,

lout also closed at lts ends, fits over the trame 2l and rests against the plate 2li, thus enclosing the trame.

This cover it has an opening in the back. thereof. Outside the opening 2t, there ts a diaphragm mechanism including a relatively rigid cup-like member anged as at 2&5. Screws 2l pass through the flange through the cover Z3 and engage in the trarne il, thus securing the diaphragm mechanism and the cover rigidly to the frame.

'Fitting closely within the cup-like member there is a cup-litre diaphragm element 2&3. The diapliragin element il@ and the member 2E are welded together about their side walls as at 29. Normally the end wall of the element 2t is contiguous throughout its area to the correspending end wall oi the member il. tube d@ projects from one corner of the member i5 and terminates in a sullo 3l. in, the preferred construction the tuhe is of capillary size, and the l mechanism is oi the solid-charge type wherein the hulle, the tuhe and all spaces that may exist between the element and .the member are entirely filled with a liquid that expands in respense to heat changes hut continues in the liquid state throughout the normal range ci operation. Thus when the liquid within the bullo 3l heats and expands, it will force the diaphragm 2&3 (especially the end wall) away from the rigid cup member 25; and the reverse action will ocn cur upon cooling oi the liquid within the bulb.

The transmission :means includes a stud that is maintained in contact with the flexible diaphragm til. This stud passes through an opening .it in the hach wall. of the frame 2l and has a ilange 3l therearound near the end til, which latter end rests against the diaphragm A cup-like washer t9 has a iiange il@ that may pass through the hole in the frame 2l and surrounds the stud A conical coil spring the stud and the washer This spring normally urges vthe contact end .it Iagainst the diaphragm 2&3.

'To prevent the stud 35 from rotating, for a purpose to be described, a pin t2 passes therethrough and is secured therein. This pin extends beyond the limits of theside walls of the frame El. These side walls, as well as the back wall, are slotted as at 43, in which slot the pin 42 is guided for reciprocal movement toward and from the front of the instrument. The slots are such as to permit such reciprocal movement but to prevent any substantial rotary movement.

'I'he front end of the stud ll is threaded as at to receive a sleeve It, and to the outer endofthesleeveissecuredadialpiate 41 and a rotating knob Il. This sleeve 4l is rounded on its inner end as at 40. against which rounded portion there ilts a spherical washer il. It 'will be seen that the sleeve moves in and out to follow the movements of the stud 20 as the iatter follows the movements of the diaphragm 20. A pivot shaft l2 passes through the side walls of the frame 2| near and slightly below the stud 2l. A primary lever I2 has upturned ears Il through .which the shaft l2 passes. This primary lever likewise has an opening Il through which freely passes the stud Il. '0n opposite sides of the opening Il are upstanding projections ll that engage against the washer l0.

A backturned ear l1 on the primary lever nts within a coil spring Il, the other end of which is held in position by being received in an opening Il in a bracket I that has a further function to be described. The spring u acts to urge the primary lever frontward toward the washer Il, as will be described.

'I'he primary lever I2 at its upper end is forked, as shown in Fig. l2, giving it two arms 0|, the ends of which are turned back at l2.

A long secondary lever 00 extends substantially the full length of the instrument. At its upper end it has a metal portion Il which has at its sides frontwardly bent portions located opposite the backturned portions I2 on the primary lever. A bronze strip 1| is, attached between these corresponding oppositely disposed portions 02 and 10 on the primary and secondary levers. I'his stripis riveted to the primary lever by rivets 12 that maintain the strip 1| between the turned portions l2 and suitable washers 13. Likewise rivets 'Il bind the strip 1| between the turned portions 10 on the secondary lever and washers 15.

'I'he bronze strip 1| acts as a hinge connection between the primary and the secondary lever. Obviously, this is a frictionless connection.

The metal end Il of the secondary lever 60 likewise has a forwardly turned end portion 11 located medially thereof, and a short distance upwardly from the strip 1|. A differential lever 10 has uptumed ears 'Il that engage over the pivot shaft $2 (Figs. 6, 7, ll). 'I'he lever likewise has a large central opening 00 that lits around the stud 36 and the spring 50. This diiferential lever is provided with a forwardly turned portion Il that may be struck out in the formation of the opening Il. A bronze hinge strip 82 is secured to the portion 0| and the portion 'I1 whereby the secondary lever is pivoted to the differential lever. Rivets 03 with suitable washers secure the bronze hinge l2 to the portion 0|. Rivets or screws 0I secure the hinge i2 to the secondary lever.

'Ihe differential lever has a notch Il mits upper edge that projects over the bracket 60. A screw 00 threads into the bracket Il and passes through the notch This screw has a nange 81 on the opposite side of the dierential lever. The screw .projects forwardly through a notch in the front plate 2l and is provided with a bearing Il in a plate I0 attached to the front plate 20. In front of the instrument, the screw Il has a gear portion l0, and-a kerfed portion 0| thereon, by means of which it may be rotated. It

will be observed that its rotation will move the flange 01 toward or from the bracket 0I.

The plate l has an opening through which the sleeve Il passes. A collar l2. nanged at Il.

passes through this hole and is secured to the plate 00 within the hole. This collar 02 supports the sleeve I0 for its reciprocal movements. Inside the flange Il there is mounted a gear sector Il which rotates on the collar. This gear sector is maintained against the flange Il by an annular leaf spring Il that engages between a washer Il and the gear sector.

The gear I4 (Fig. 4) carries stops l1 and Il that limit rotation of the gear sector by their abutting the gear 00. There is also provided on the sector a pointer 20 having an index |00 that extends over the dial 41.

Anadditional ilxed pointer |0| is attached to the cover 23 and extends over the dial. This pointer is provided with an opening |02 through which extends the kerfed portion 0| of the screw 00.

The secondary lever t0 includes a middle portion Ill formed of insulating material, and having a large opening |00 through which passes the stud fand the sleeve 48. The lower end of the secondary lever consists of a blade portion |01 riveted at |00 to the insulating portion Ill. 'Ihe bottom end of the blade |01 is turned backward and then downward. as shown in Fig. e. To this bottom end, there is attached an armature assembly consisting of an armature element |00 and an additional armature element held `in spaced relation by a spacer ||0. As will appear hereafter, the two armatures |00 and are located on opposite sides of a horseshoe magnet.

Within the frame 2| at the switch end, there is located an insulating lining ||2. Within this lining and on the back wall of the frame 2| there is secured an insulating block H3. A permanent horseshoe magnet ||4 is secured embedded in the block by a rivet Ill engaging through tllie block and through a rigid insulating sheet 8.

The blade |01 of the secondary lever has projecting backwardly therefrom an element |`|8 in the shape of an inverted T, the smaller portion of which is secured to the blade |01, and which provides two confined spaces between the blade |01 and the cross element of the T.

A generally cross-shaped contact member ||0 (Fig. 9) has a bifurcated upper end |20 the elements of which iit in the previously mentioned spaces between the blade |01 and the head of the T-shaped element III. A suiilcient amount of play is provided to permit the opposite end of the member Ill to pivot. This opposite end of the member Il! has a tongue |2| that passes through an enlarged opening |22 in the backwardly turned portion of the blade |01. 'I'he hole |22 permits the tongue, and consequently the plate III. to be displaced a substantial, but limited, distance from the blade.

I'he contact member III has a rivet-like element |23 projecting from the back thereof. A light leaf spring |24 is attached to the secondary lever by means of the rivets |00. The shape of this leaf spring is shown by reference to Figs. 6 and 9. It is provided with an opening engaging over the rivet-like element |22 and, with a light tension. it normally urges the contact member l forwardly of the instrument until stopped by contact with the blade II'I.

'Ihe T member Il acts as a stop to limit the lthe instrument as shown shaped member the cooling the diierential lever."

The contact member ||3 ls adapted to close l 1 across two fixed terminal contacts |25 and. |21

secured to the yfront plate 20. The terminal |25 has a contact:l bracket |28 extending therefrom inside the plate 20, laterally as-shown in Fig. 8, and from this lateral portion backwardly and upwardly to provide a portion |23 supporting a contact |30. The contact |38' is thus located beneath one side of the cross-shaped memberl I9. The'terminal |21 has a bracket |32 secured theretoinside the Yplate 20. This bracket is bent backwardly along the side wall inside the lining ||2, and'likewiseV projects downwardly, as shown at |33`in Fig. 2. The downwardly projecting por- 34 and .|35 struck out therefrom, these legs projecting towards the center of A in,Fig.-8. The leg |35 has secured thereto acontact |38 spaced opposite the contact I 30 beneath the other side of the cross- 9. It will'be seenA from the foregoing that the member I9 may be brought toward the `front .of the instrument so that it the back of the instrument so as to break the connectionjbetween said contacts. The leg |34 The operation Theinstrument may be used as a refrigeration switch as here shown. The bulb 3| is placed in chamber, the temperature of which is .to'be controlled. The switch is located at a conveniente-and accessible point, it being connected to the bulb bythe capillary tube 3B. The terminals |25 and |21 are connected in series with part of, the refrigeration mechanism, such as the compressor motor. y

When the liquid within the bulb expands, because of increasedheat.' the diaphragm 28 will be moved outwardly'toward the front of the instrument. It will be carryv with it the stud 35 which moves against the spring 4| and is guided lthrough the openings in the `washer 39'and the collar 93. This forward movement of the stud carries with it the sleeve 46, since the two are `threaded'together.v The primary lever 53 willbe caused "to follow the forward movement of the stud by ,the-action ofthe spring 58 which maintains the Ylugs 56' against the spherical washer 50, or; as'far forwardly as' is permitted. The prislight distance. I f

In this movementr the bronze hinge 1 I, between the primary. andsecondary levers, is likewise displaced toward the front of the instrument. This moves'fthe secondary lever'68, the movement of Which-is determined A`by` the bronze hinge 82 and movement of 'thel secondary lever is the 'drawing of the-portion 8|. vor the diierential lever 18 forwardly of vthe' instrumentuntil the notched portion. 85 of the lever 18T engages theflange 81 on the adjusting screw-86. soon-as the lever 18 lodges against this angeurther forward movement of .the'diifer'ential Vlever and of the upper end of the secondary leveris prevented. There-.. after, additional forward movement of the upper end of theV primary lever 1| will `produce the second stage of movement of the secondary lever, consisting of a.v rotational displacement of the upper end thereof, in a manner to be described.

This rotation' first seeks to draw the lower end ','Therst stage of the |||1` of the secondary lever to the right in Fig. 6. However, at the start of this movement, the armature isclose to the poles on the magnet ||4 and therefore resists displacement. The force of this resistance is very great when applied against the force of the primary lever, because it is appliedfwlth a tremendous mechanical advantage, by virtue of the great length of the secondary lever between its lower end and the pivoted hinge 82 in proportion to the very -small length between the primary lever hinge 1|, at

|36, or moved toward which the force of the primarylever is applied, and the secondary lever hinge 82. Since the secondary lever is somewhat resilient, there will be an" actual displacement of its upperend by the primary lever, which displacement will be absorbed in the end secondary lever, deforming thesame slightly but without displacing they lower end. f

The third stage of the movement occurs'when.

the force of the'primary lever, .plus the stored up energy in the deformed secondary lever, exceeds the resistance of the magnet. At such time thearmature will be drawn away Iromthe magnet. `As the 'power ofthe Ymagnet decreases exponentially as the armature moves'away from .mary lever thus moves clockwise in Fig 6 a v the magnet, the speed of withdrawal of the armature will increase as the lever moves forwardly, once the motion has been initiated. Furthermore, as soon as the .lever has beenv displaced a short distance, the 'other armature -I 09 approaching the magnet, will be nearer the magnet than is the rst one, so that the movement of the end of the secondary lever is effected with a snap action. 1

As the secondary lever approaches the two-con- Vtacts |30 and |36,the relatively movable cross` shaped contact member ||9 will be maintained forwardly through the action of the leaf spring |24. When the member ||9 closes with the two contacts, a furtherslight movement of the secondary lever is permitted, until the'v tongue I2-| on the member. l B reaches the backward limit of the opening. |22, and the bfurcated lends |28 strike the headof the 'T-shaped. member IIB.

'I'hel switch will stay in this position until ,the bulb 3| cools down. Theliquid will thencontract and the diaphragm` 28 will move to the back of the instrument. The spring 4| will cause the stud 35 to follow this movement. The sleeve 4B'will likewise be drawn backwardly, carrying the washer 5|lwith it. This washer, acting onthe lugs 55, will pivot the primary levery 53 counterclockwise (in Fig. 6) against the action .of the spring 58. This action of the primary lever will displace the hinge 1| between it and the secondary lever toward the back of the instrument. The upper end of the secondary lever will be'moved correspondingly. In the rststage of this movement, the

`hinge 82, between the secondary lever' and the diierential lever, will displace the differential lever counterclockwise (in Fig. 6) nntil it strikes the bracket 60.' In the second stage of' such...

movement, the lupper end of the secondary lever 'will pivot clockwise about the hingen.v This movement of the upper part of the secondary lever tends to shift the lower part of the lever away from the contacts |30 and |35. Such movement is resisted by the effect of the magnet i4 on the armature |09. lThereforey the. `second stage of movement of the secondary lever consists of a storage of the energy of displacement between the upper Aand lower ends of the lever and this produces a deformation of the lever.

The third phase of'movementsoccurs when the energy thus stored, coupled with the dynamic energy of the primary lever, overcomes the resistance of the magnet.

'Ihe secondary lever then' withdraws with a snap action ultimately augmented by the movement of the other armature lil intothefleldofthemlgnet.

Should the? contacts |80 and il! be welded to the contact member Il., the first part of the is maintained against rotation by the engagement of the rod 42 in the slots 43. It will be observed that the slots 4I are a substantial distance from the axis of the stud Il. Consequently. a relatively free t of the rod 42 within the slots 4I permits only a small angular displacement of the stud 35.l

Such angular displacement is substantially less than would be permitted by a similarly tolerant engagement close to the stud itself.

In the forward movement of the stud, responsive to increase of heat in the power means, the

primary lever is caused to follow the washer i on the sleeve 4I until it is stopped by final engagement of the contact member III on the secondary lever with the contacts Ill and 134. Any further movement of the stud 3l has no effect upon the primary lever and puts no strain on the instrument, since in such case the sleeve 46 merely moves away from the primary lever.

The fact that the mechanism is la solid-charge device enables a tremendous multiplication of power to be had. Consequently, the practically invariable action of the bronze hinges is particularly advantageous. A small change at the upper end of the levers would, of course, make a very large change at the critical switch end.

It will be observed that in the first stage of movement of theA secondary lever, when it dislever 18 tovmove, the pivoting of both the pri- .movement of the secondary lever will take. place vus mary and differential levers about the same center eii'ects a pivoting of the secondary lever with out distortion of either hinge Il or 82.

The adjustments be required before the-sleeve is restored to its, voriginal position. Thus the switch is adjusted to move at a higher temperature.` Conversely, if the knob 48 is moved to withdraw the sleeve 46 toward the front of the instrument, the primary lever is advanced so that less increase in heatin the bulb is required to shift the secondary lever.

'I'he adiustment of the differential mechanism is obtained by inserting a screw driver in the kerfed portion 9| on the screw I6 and rotating the screw to alter the position of the flange Il.

This displaces the ange il toward or from the bracket Il, altering the length ofthe rst stage of movement of the secondary lever.

If the instrument be set by knob 4l to open at 35 it will always do so. However, if the pointer |04 be set at 40', such will occasion such displacement of the ilange Il so that an additional 5 of movement of the diaphragm is required to complete the nrst stage of movement of the secondary lever, it being obvious that subsequent stages take place only upon completion of the rst.

In adjusting the differential, the gear shifts the sector 04 and carries the pointer IIII over the dial 41 to indicate the temperature at which the switch closes. In this operation, the sector I4 rotates on the collar l2. Thus the pointer Ill indicates the opening temperature of the switch and the pointer III indicates the closing temperature.

What is claimed is:

l. In a mechanism of the kind described,a pair of levers. a hinge joining the two levers, a bracket, a hinge between one lever and the bracket. and means providing limited movement for the bracket in the direction of movement of the lever attached thereto.

2. In a mechanism of the kind described, a pair of levers, a hinge joining the two levers, a pivoted bracket, a hinge between one lever and the bracket, and a pair o'f spaced and relatively adjustable abutments on opposite sides of the bracket to permit controlled and limited movement of the bracketin the direction of movement of the lever attached thereto.

3. In a mechanism of the kind described, a lever, means to move the lever in opposite directions, a bracket pivoted about an axis parallel to the axis of the lever, a pair of spaced abutments on opposite sides of the bracket, at least one of which is adjustable, means for adjusting said adjustable abutment, and a hinge between the lever and the bracket, said hinge being displaced from the pivoted part of the bracket.

4. In a mechanism of the kind described, a primary lever, a pivot therefor, a secondary lever, means hinging the primary lever to the secondary lever, a differential lever operating on the pivot of the primary lever, adjustable abutments on opposite sides of the differential lever to permit limited movement thereof, and means hinging the secondary lever to the dierential lever.

5. In a mechanism of the kind described, a frame, a primary lever having spaced and down-` turned ears at one end thereof, a secondary lever having at one end correspondingly spaced and downturned ears, flexible hinge strips secured between the ears of the primary and secondary levers, a third ear on the secondary lever between the first two, and projecting a slight distance beyond the first two, and means including a flexible strip joining the third ear to the frame.

6. In a mechanism of the kind described, a power means, a frame, a member on the frame and moved by the power means. means extending from the member and guides on the frame engaging the member to prevent angular movement of the member, an adjustable sleeve on the member, a. primary lever, means urging the primary lever` against the sleeve to follow movements thereof, a secondary lever, means hinging the primary lever to the secondary lever adjacent one end of the latter, means at the end of the secondary lever hinging the same to the frame, the length of the secondary lever from its ing` the contacts for A to the secondary lever.

Y 2,291,502. free end to its primary lever hinge being a large multiple of its length from the primary lever to the hinged end, switch contacts at the free end of the secondary lever. snap action means at the free end of the secondary lever, the secondary lever being resilient, and-means mountlimited movements relative '1. In a switch mechanism.A a frame having front, back and two side walls, a power means including a' cup-shaped member enclosing a nei;- ible diaphragm, a stud and` a sleeve threaded on one end thereof, the stud passing through the back wall, means maintaining the stud against the diaphragm, the sleeve passing through the front wall, switch mechanism actuated by movement of the stud and sleeve in. response to displacement of the diaphragm, movement of the sleeve on the stud adjusting the operation oi the switch mechanism, and a pin passing through the stud with guide means in. the side wall c0- acting with the pin to prevent rotation of thek stud,but permitting axial movement thereof.

frame. a primary lever pivotally attached to 8. In a mechanism of the kind described. a frame, a primary lever having a iiat surface adjacent to one end thereof, a secondary lever having a corresponding surface disposed approximately at said primary lever surface, a exible hinge strip extending across between said levers and attached to said surfaces, an additional surface on the seconda-ry lever spaced beyond the hinge strip, and means including a ilexible strip attached to said additional surface, joining said secondary levez` to the frame.

9. In a mechanism of the kind described, a said frame, a secondary lever, a hinge strip connecting said primary and secondary levers, and disposed substantially tangentially to the direction of movement of the primary lever, and means attaching the secondary lever pivotally to the frame for movement in a direction substantially concentric with the direction of primary lever.

LAWRENCE NL PERSONS.

movement of the 

